Investigation of high temperature electrostatic precipitation for implementation in a solar reactor

Abstract

High–temperature solar reactors, which directly heat particle materials, are one of the promising paths leading to more sustainable industrial processes. In case of controlled atmosphere processes, the presence of a window could strongly increase the system efficiency. Nevertheless, so far, particle deposition on the window remains a challenge. This paper proposes an innovative solution to keep the window clean based on the electrostatic separation of particles. A high–temperature electrostatic window protection system for the geometry of an existing solar reactor has been designed, constructed and experimentally demonstrated. The system can be integrated into the reactor using its aperture region as a grounding electrode. To design a suitable electrical insulator, dielectric strength measurements were performed on standard aluminium oxide tubes, showing the need of cooling the discharge electrode connection below 807 K. This system was designed and proven. The corona generation process was characterised in air and CO2 between 633 and 933 K. Stable corona discharges were observed in all tests, using both positive and negative polarities. Positive polarity allowed for a more stable corona discharge and a wider operating range. For example, at 833 K in the case of CO2, the maximum voltages were about 19 and 16 kV for the positive and negative discharges, respectively. Preliminary tests with particles at 933 K showed the system’s potential to reduce the transmissivity loss through the window by about 70%. With this promising finding, a future study is planned to further improve this result by modifying the operating conditions.